Liquid-cooled internal combustion engine

ABSTRACT

A liquid-cooled internal combustion engine, including at least one cylinder block which has a cooling jacket and multiple cylinders. The cooling jacket has a base facing toward a crank chamber and a top facing toward a cylinder head sealing plane. The base has an undulating profile in which a first distance, as measured in the direction of the cylinder axis, between the base of the cooling jacket and the top in the region of at least one first engine transverse plane which encompasses the cylinder axis is greater than a second distance in the region of at least one second engine transverse plane between two adjacent cylinders. In order to reduce cylinder deformation, the cooling jacket has three different heights, in which a third distance between the base of the cooling jacket and the top is smaller in at least one face-end region of the cooling jacket.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage Application of PCTInternational Application No. PCT/EP2012/052365 (filed on Feb. 7, 2013),under 35 U.S.C. §371, which claims priority to Austrian PatentApplication No. A 50027/2012 (filed on Feb. 8, 2012), which are eachhereby incorporated by reference in their respective entireties.

TECHNICAL FIELD

The invention relates to a liquid-cooled internal combustion engine,comprising at least one cylinder block which has a cooling jacket andmultiple cylinders, wherein the cooling jacket has a base facing towarda crank chamber and a top facing toward a cylinder head sealing plane,and the base has an undulating profile as seen in a side view of thecylinder block, wherein a first distance, measured in the direction ofthe cylinder axis, between the base of the cooling jacket and the top inthe region of at least one first engine transverse plane whichencompasses the cylinder axis is greater than a second distance in theregion of at least one second engine transverse plane between twoadjacent cylinders.

BACKGROUND

U.S. Pat. No. 5,080,049 A describes a cylinder block for an internalcombustion engine with several cylinders, wherein the cylinders aresurrounded by a cooling jacket. The cooling jacket has an undulatingprofile on one longitudinal side of the cylinder block, wherein thedistance of the base of the cooling jacket from the cylinder headsealing plane is smaller in the region of an engine transverse planecontaining the cylinder head screw axes than in the region of a firsttransverse engine plane which contains the cylinder axis.

A liquid-cooled internal combustion engine with a similarly shapedcooling jacket is also known from Austrian Patent Publication No. AT 504983 B1.

Japanese Patent Publication No. JP 2011-106 398 A1 discloses a coolingstructure for an internal combustion engine, wherein the cooling jackethas a uniform height in the first and second engine transverse planes.The distance between the base and the top of the cooling jacket is onlysmaller in the region of a face side than in the other area.

WO 95/21323 A1 discloses a cooling system of a two-stroke internalcombustion engine with several cylinders which are surrounded by acooling jacket. The base of the cooling jacket is provided with anundulating profile and is flow-connected to a bottom coolant collectorvia U-shaped branch passages and vertical channel sections in the regionof the engine transverse plane between two cylinders.

A cooling jacket for a crankcase is further known from Chinese PatentPublication No. CN 2 751 151 Y, whose cooling jacket base is formed inan undulating fashion as seen in a side view. The cooling jacket has asmaller distance from the cylinder head sealing plane in the region of afirst engine transverse plane containing the cylinder axis than in theregion of a second engine transverse plane between two cylinders. Thecooling of thermally highly loaded regions is thus to be improved.

Relatively large cylinder deformations can especially occur in theregion of the outer cylinders.

SUMMARY

It is the object of the invention to avoid this disadvantage and toreduce the deformations of the outer cylinders.

This is achieved in accordance with the invention in such a way that thecooling jacket has three different heights, wherein a third distancebetween the base of the cooling jacket and the top is smaller in atleast one face-end region of the cooling jacket—preferably in the regionof an engine longitudinal plane spanned by cylinder axes—than in theregion of the second engine traverse plane between two adjacentcylinders.

Especially good results can be achieved if the distance between the baseand the top in at least one face-end region is up to approximately 90%,preferably between approximately 50% and 70%, of the distance betweenthe base and the top.

As a result of the constriction in the direction of the cylinder axis inthe face-end region of a cooling jacket, cooling in this region can bereduced on the one hand and thus a constant temperature profile of thecylinder block is achieved, and the structure of the cylinder block canbe stiffened decisively on the other hand and deformations can thus bereduced to a substantial extent.

DRAWINGS

The invention will be explained below in greater detail by reference tothe drawings, wherein:

FIG. 1 illustrates a cooling jacket of a cylinder block in accordancewith the invention in a side view in a first embodiment.

FIG. 2 illustrates the cooling jacket in a top view.

FIG. 3 illustrates the cooling jacket in a front view.

FIG. 4 illustrates a cooling jacket of a cylinder block in accordancewith the invention in a side view in a second embodiment.

FIG. 5 illustrates fourth-order deformations for an outer cylinder in aknown cylinder block and a cylinder block in accordance with theinvention.

DESCRIPTION

FIGS. 1 to 3 illustrate a cooling jacket 1 of a cylinder block (notillustrated in closer detail) of an internal combustion engine with fourcylinders 9, said cooling jacket 1 surrounding cylinder liners. Asillustrated in the side view of FIG. 1, the base 2 of the cooling jacket1 is shaped in an undulating fashion, so that the distance H of the base2 increases and decreases from the cylinder head plane 3, as seen in thelongitudinal direction of the cylinder block. In detail, the distance Hin the region of a first engine transverse plane 5 containing thecylinder axis 4 is greater than in the region of a second enginetransverse plane 7 extending between two cylinders, e.g., through theaxes 6 of the cylinder head screw bores for the cylinder head screws.

The distance H2 between the base 2 and the top 3 of the cooling jacket 1is smaller in the face-end region 8 of the outer cylinders 9, especiallyin the region of the engine longitudinal plane 13 spanned by thecylinder axes 4, than in the region of the second engine transverseplanes 7 between the two cylinders 9. The distance H2 between the top 3and the base 2 is approximately 50% to 80% of the maximum distance H inthe face-end region 8 of the front side 1 a, 1 b between the top 3 andthe base 2 in the region of the first engine transverse plane 5.

FIG. 4 and FIG. 6 illustrate a cooling jacket 1 for a three-cylinderinternal combustion engine, in which the profile of a known coolingjacket is illustrated in FIG. 4 in comparison with the proposal inaccordance with the invention with the dashed lines 10. A considerableimprovement in the cylinder deformation of the fourth order in theregion designated with reference numeral 11 of the deformation diagramshown in FIG. 5 is achieved by reducing the distance from H2′ to H2. Theoriginal deformation profile is designated with the dashed line 12′ inthe deformation diagram of FIG. 5 and the deformation profile withreduced distance H2 is designated with reference numeral 12.

The stiffness of the cylinder block can be increased substantially byreducing the distance H2 between the top 3 and the base 2 of the coolingjacket 1 in the face-end region 8 of the cooling jacket 1 adjacent tothe outer cylinders.

1-5. (canceled)
 6. A liquid-cooled internal combustion engine, comprising: at least one cylinder block which has a cooling jacket and a plurality of cylinders, wherein: the cooling jacket has a base facing toward a crank chamber and a top facing toward a cylinder head sealing plane, the base having an undulating profile as seen from in a side view of the cylinder block, in which a first distance, as measured in a direction of a cylinder axis, between the base and the top in a first region of at least one first engine transverse plane which encompasses the cylinder axis, is greater than a second distance in a second region of at least one second engine transverse plane between adjacent cylinders; and the cooling jacket has three different heights, in which a third distance between the base and the top is smaller in at least one face-end region of the cooling jacket than in the region of the second engine traverse plane between two adjacent cylinders.
 7. The internal combustion engine of claim 6, wherein the third distance between the base and the top is smallest in at least one face-end region.
 8. The internal combustion engine of claim 6, wherein the third distance between the base and the top in at least one face-end region is up to approximately 90% of the distance between the base and the top.
 9. The internal combustion engine of claim 6, wherein the third distance between the base and the top in at least one face-end region is up to between approximately 50% and 70% of the distance between the base and the top.
 10. The internal combustion engine of claim 6, wherein the third distance is formed in both face-end regions of the cylinder block between the base and the top.
 11. The internal combustion engine of claim 6, wherein the base has a circular profile in at least one face-end region. preferably in both face-end regions (8).
 12. The internal combustion engine of claim 6, wherein the base has a circular profile in both face-end regions.
 13. A liquid-cooled internal combustion engine, comprising: at least one cylinder block having a plurality of cylinders; and a cooling jacket surrounding the at least one cylinder block, the cooling jacket having a base facing toward a crank chamber and which has an undulating profile, a top facing toward a cylinder head sealing plane, and a plurality of heights that differ from each other, wherein: a first distance, as measured in a direction of the cylinder axis, between the base and the top in a first region of at least one first engine transverse plane which encompasses the cylinder axis, is greater than a second distance in a second region of at least one second engine transverse plane between adjacent cylinders; and a third distance between the base and the top is smaller in at least one third region of an engine longitudinal plane spanned by cylinder axes, than in fourth region of the second engine traverse plane between adjacent cylinders.
 14. The internal combustion engine of claim 13, wherein the third distance between the base and the top is smallest in at least one face-end region.
 15. The internal combustion engine of claim 13, wherein the third distance between the base and the top in at least one face-end region is up to approximately 90% of the distance between the base and the top.
 16. The internal combustion engine of claim 13, wherein the third distance between the base and the top in at least one face-end region is up to between approximately 50% and 70% of the distance between the base and the top.
 17. The internal combustion engine of claim 13, wherein the third distance is formed in both face-end regions of the cylinder block between the base and the top.
 18. The internal combustion engine of claim 13, wherein the base has a circular profile in at least one face-end region. preferably in both face-end regions.
 19. The internal combustion engine of claim 13, wherein the base has a circular profile in both face-end regions. 